#include <SFML/Graphics.hpp>
#include <time.h>
using namespace sf;

int N = 30, M = 20;
int size = 16;
int w = size * N;
int h = size * M;

int dir, num = 4;

struct Snake
{
	int x, y;
}  s[100];

struct Fruit
{
	int x, y;
} f;

void Tick()
{
	for (int i = num; i > 0; --i)
	{
		s[i].x = s[i - 1].x; s[i].y = s[i - 1].y;
	}

	if (dir == 0) s[0].y += 1;
	if (dir == 1) s[0].x -= 1;
	if (dir == 2) s[0].x += 1;
	if (dir == 3) s[0].y -= 1;

	if ((s[0].x == f.x) && (s[0].y == f.y))
	{
		num++; f.x = rand() % N; f.y = rand() % M;
	}

	if (s[0].x > N) s[0].x = 0;  if (s[0].x < 0) s[0].x = N;
	if (s[0].y > M) s[0].y = 0;  if (s[0].y < 0) s[0].y = M;

	for (int i = 1; i < num; i++)
		if (s[0].x == s[i].x && s[0].y == s[i].y)  num = i;
}

int main()
{
	srand(time(0));

	RenderWindow window(VideoMode(w, h), "Snake Game!");

	Texture t1, t2;
	t1.loadFromFile("images/white.png");
	t2.loadFromFile("images/red.png");

	Sprite sprite1(t1);
	Sprite sprite2(t2);

	Clock clock;
	float timer = 0, delay = 0.1;

	f.x = 10;
	f.y = 10;

	while (window.isOpen())
	{
		float time = clock.getElapsedTime().asSeconds();
		clock.restart();
		timer += time;

		Event e;
		while (window.pollEvent(e))
		{
			if (e.type == Event::Closed)
				window.close();
		}

		if (Keyboard::isKeyPressed(Keyboard::Left)) dir = 1;
		if (Keyboard::isKeyPressed(Keyboard::Right)) dir = 2;
		if (Keyboard::isKeyPressed(Keyboard::Up)) dir = 3;
		if (Keyboard::isKeyPressed(Keyboard::Down)) dir = 0;

		if (timer > delay) { timer = 0; Tick(); }

		////// draw  ///////
		window.clear();

		for (int i = 0; i < N; i++)
			for (int j = 0; j < M; j++)
			{
				sprite1.setPosition(i*size, j*size);  
				window.draw(sprite1);
			}

		for (int i = 0; i < num; i++)
		{
			sprite2.setPosition(s[i].x*size, s[i].y*size);  
			window.draw(sprite2);
		}

		sprite2.setPosition(f.x*size, f.y*size);  
		window.draw(sprite2);

		window.display();
	}

	return 0;
}
